The invention relates to a round steel chain of hingedly interconnected chain links.
Chains are formed from a plurality of chain links arranged successively to form an open or a closed chain strand. The individual chain links can be interconnected for example by releasable hinges or directly hingedly joined with one another. Chains serve predominantly as heavy-duty traction means having a force direction which due to the hinged configuration is also deflectable.
Round steel chains are formed from directly interengaged chain links, which at least in some sections have a rounded cross section. Such a chain link of steel is formed, for example, from a round rod of corresponding length, which is first correspondingly shaped, whereupon its free ends are joined together.
In underground coal mining, round steel chains are used for example for operation of coal planes or for continuous transport of recovered excavations. In particular during transport, they are pulled as circulating conveyor chains over a conveyor trough and deflected at the end. Since in the chain strand the chain links engaging one another with their bends are already structurally arranged rotatably relative to one another, they are differentiated as alternating horizontal and vertical links.
To increase the transport quantities of such facilities, the performance has to be increased. As a result, the forces to be transmitted are increased, so that the individual chain links must be sized larger. While the horizontal links due to their parallel orientation to the trough have enough space available, the corresponding upright vertical links are contrary to the desire for a lowest possible height. Therefore, in particular the vertical links are formed in the art as flat links, and their height can be reduced by border-side flattening of the chain legs.
DE 103 48 491 B3 discloses a round steel chain link with hingedly interconnected chain links, with the chain legs of at least every second chain link being flattened in cross section at the margin to form a flat link. The chain legs of the flat links have a greater leg width in relation to the diameter of the chain bends. As a result, the regions of the chain legs extending beyond the diameter to the leg width form lateral bulges which extend to the chain bends or into the chain bends.
The bulges allow a further reduction of the height of the flat links, since the lacking material volume due to the flattenings are displaced into the cross section of the bulges. As a result, the required cross sectional area is maintained despite smaller height dimensions.
In particular the contact surfaces located between the interengaging chain bends of the individual chain links are subject to increased wear both with respect to the normal chain links and also with respect to the flat links. In addition to the applied tensile force which must be transmitted via these contact surfaces, the required mobility between the chain links leads to high friction which causes correspondingly high wear.
Against this background, there is generally still room for improvements when designing round steel chains in particular in the region of the interengaging chain links.